Gov. Dave Heineman announced Saturday that he will not seek Nebraska's open Senate seat, inviting a free-for-all in the Republican primary.

"After careful consideration of all of the issues involved in a race for the United States Senate, I have decided to keep my focus on being the best Governor that I can for the citizens of Nebraska," Heineman said in a Saturday morning email to supporters. "A race for the United States Senate would distract from the State’s priorities of tax relief, job creation and education."

Instead, his decision turns attention to the state's three Republican members of Congress: Jeff Fortenberry, Lee Terry and Adrian Smith.

Some GOP insiders believe Fortenberry is the most likely to run. Another potential candidate is former state Treasurer Shane Osborn, who considered running for Senate last year.

The Associated Press reports that other Republican who may be interested in the seat include Nebraska Attorney General Jon Bruning and state Treasurer Don Stenberg, who both ran for Senate in 2012, as well as 2006 Senate candidate Pete Ricketts.